Question

I am getting Segmentation error(core dump) in the following code:

void Update_Log( )
{
        struct logData update;
        int file;

        char *writeBuffer=NULL;

        if((file=creat("/home/user/Desktop/DMS/DMS/filename.txt",O_RDONLY|O_WRONLY))==-1)
                perror("file not opened");
        update.clientName="user";
        update.filename="user";
        update.timestamp="some time";
        sprintf(writeBuffer,"%s %s %s",update.clientName,update.filename,update.timestamp);


        if((write(file,writeBuffer,sizeof(writeBuffer)))==-1)
                perror("write unsuccessful");
        close(file);
}

My structure is as follows:

struct logData
{
        char *clientName;
        char *filename;
        char *timestamp;
};

Can anyone help in this?

Answer 1

You’re trying to write to writeBuffer which is a null pointer, you should declare it as array(1), or allocate a memory on the heap(2) for it.

1. char writeBuffer[100];
2. char *writeBuffer=malloc(100)

in both cases you should not use sprintf, but snprintf to make sure you are not overflowing your buffer.